Palmitoyl-7?-lysine

Biocompatible cationic surfactants from the amino acid lysine (hydrochloride salts of A -lauroyl-lysine methyl ester, IV -miristoyl-lysine methyl ester and A -palmitoyl-lysine methyl ester) show moderate antimicrobial activity against the Gram-positive bacteria. The haemolytic activity of these compounds is considerably lower than those reported for other cationic Ai -acyl amino acid analogues [64]. Taking into account the high biodegradation level and the low haemolytic activity, these compounds could be considered safe surfactants in relation to the cell of the human body. These properties make them suitable candidates for biological and medical applications [65]. 

Uchegbu and coworkers have studied the complexation and delivery of DNA using a unique poly(amino acid)-based polymer vesicle. A polymer of either poly (L-lysine) or poly(L-omithine) was functionalized with methoxy-poly(ethylene glycol) (mPEG) and hydrophobic palmitic acid chains to synthesize an amphiphilic triblock of either mPEG-6-poly(L-lysine)-6-palmitoyl or mPEG-Z>-poly(L-omithine)-6-palmitoyl. Vesicles formed from these polymers were complexed with DNA and showed improved transfection in vitro over poly(amino acid) complexed with DNA or DNA alone [82]. 

Figure 8.11 Formation of pyramidal crystals of a-glycine attached to the /V palmitoyl-(R,S) -lysine monolayers. (Reproduced with permission from [16]).

Figure 7.2 Palmitoyl-R-lysine monolayers on water are not only stabilized by binding interactions between the hydrocarbon chains and amino acid head groups, but linear amide hydrogen bonds between the e-amide groups are also formed. This requires a 30° tilt.

Figure 7.3 Reflectivity data of the palmitoyl-R-lysine monolayer (see Figure 7.2) in the presence ofS-glutamine in the subphase show that about one quarter of the sites below the lysine head groups are occupied by glutamine. Amide hydrogen bonds cause the enrichment of glutamine on the surface charge interactions between the a-amino acid moieties also stabilize the hydrophilic glutamine layef.

Hackett M, Guo L, Shabanowitz J et al. (1994) Internal lysine palmitoylation in adenylate cyclase toxin from Bordetella pertussis. In Science 266 433-435. 

CaaX sequence and is famesylated, proteolyzed, and methylated, but this protein lacks upstream cysteines and is thus not palmitoylated. Instead, K-ras has a run of several lysine residues that have been shown to increase the affinity of the protein for the membrane, possibly by electrostatic interactions with the negatively charged phospholipid bilayer (Hancock et al., 1990). 

A new polymeric amphiphile based on cationic poly(L-lysine), which was partially modified with hydrophobic palmitoyl chains and hydrophilic neutral methoxy-poly(ethylene glycol) (Fig. 7e), was introduced by Uchegbu et al. [38,39], In water in the presence of cholesterol, these copolymers assembled into vesicles with diameters ranging from 200 to 600 nm (DLS, freeze-fracture TEM), depending on the chemical composition of the copolymer and the length of the polypeptide backbone. More detailed information about the secondary structure of chains and the structure of vesicle membranes were not given. 

Lipacide LML. See Lysine lauroyl methionate Lipacide PCA. See Palmitoyl hydrolyzed milk protein... 

Mammalian cells have three Ras proteins, Ha-Ras, Ki-Ras and N-Ras, which are present in most cell types. They are bound to the cytoplasmic surface of the plasma membrane by (i) a famesyl moiety bound by a thioether linkage to the C-terminal cysteine residue whose carboxyl group has been methylated by SAM (see) and (ii) a palmitoyl residue bound by a thioester linkage to a cysteine residue 2-5 residues from the C-terminus in the case of Ha- and N-Ras, or a polybasic domain containing six lysine residues in the case of Ki-Ras. 

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